Pressure regulators currently used are also commonly known as “pressure reducers” because their regulating action is achieved by reducing the gas delivery pressure through laminar flow elements.
Regulators known in prior art basically comprise a main body with an inlet through which gas flows in at high pressure and an outlet through which the gas flows out at reduced pressure. This main body houses means for controlling and regulating the gas flow.
The controlling and regulating means comprise at least one shutter, actuated by spring and diaphragm systems which enable the shutter to slide on its shaft, and a pilot device which measures the pressure of the gas upstream and downstream of the regulator and controls the shutter actuating diaphragm accordingly.
In other words, the diaphragm divides the volume delimited by two flanges into two chambers. The pressure in one of the chambers is a regulating pressure set by the pilot device whilst the other chamber is in fluid communication with the pipe downstream of the outlet and, therefore, the pressure in it is the aforementioned reduced pressure.
During operation under balanced conditions, that is to say, when the pressure upstream and downstream of the regulator is substantially equal, the pilot device keeps the regulating pressure constant and the shutter remains in the same position.
When the pressure downstream or upstream of the regulator varies, the pilot device changes the regulating pressure in such a way as to act on the spring and diaphragm system to change the position of the shutter accordingly.
In the spring and diaphragm system, a regulating spring acting directly or indirectly on the shutter opposes the action of the regulating pressure on the diaphragm. The spring therefore tends to close the shutter.
Usually, the change in the position of the shutter results in a change in the operating parameters of the regulator which accordingly adapts to the new conditions in order to contribute to adjusting the downstream pressure to the set value.
Routine maintenance operations involve periodically checking and substituting the seals and seal pads that are engaged by the moving parts of the regulator, that is to say, in contact with the shutter.
To do this in prior art regulators, the regulating spring acting on the shutter must be decompressed and the top of the regulator removed en bloc.
The parts to be removed are often very heavy because they are used to regulate extremely high flow rates and therefore have to oppose exceedingly high pressure. For this reason, handling them involves considerable effort and risks for maintenance personnel.
Moreover, the need to remove highly compressed, preloaded springs exposes personnel to further risk.
Other problems arise on reassembling the regulator when the spring that was decompressed and removed has to be put back into the regulator and preloaded again, an operation that may even require a special press or a complex screw-operated device.